The common way for connecting an additional circuit board, especially the printed-circuit board connection inside a computer, is to vertically mount the additional circuit boards on the mother board with a connecting socket. That kind of socket has an inlet port on either side of the socket for the add-on card to stay on proper position, as shown in FIGS. 8 and 9. Those inlet ports and the main socket body are formed in one integrated unit employing high-temperature resistant compound materials. The characteristics of these compounds are hard and easy to break. Hence, during the assembling-disassembling process of the add-on card, the inlet port is often broken. The other case is due to the compound's modulus of rigidity being very high which leads to a larger force being required to take-out or put-in a card into a socket. Thus it is more difficult to control the operation.
Furthermore, the way to fix the conventional type socket on the mother board is by means of pins on both sides of the bottom of the socket. To have a simple indication of assembly direction, the pins of different sides have different diameters. Because of this, the pin of smaller diameter is less rigid and has a high probability to break off the socket body when a force applies to it.